Patent GB-549936-A (GB)
Title: Improvements in or relating to grinding or abrading machines
IPC: B24B47/06
Filed: 1941-07-12
Abstract: 549,936. Hydraulic machines. JONES & SHIPMAN, Ltd., A. A., and HOULDSWORTH, J. July 12, 1941, No. 8835. [Class 69 (ii)] [Also in Group XXIII] A hydraulically-operated surface grinding or abrading machine comprises a horizontally disposed cross saddle 5, Fig. 1, slidably mounted on an upright 'frame 1, a work table 3 traversable across the saddle 5, a table traversing cylinder 14, Fig. 16, carried by the cross saddle and containing a piston 15 connected to the work table 3, an oil reservoir 24 and pump 25 in the base portion of the frame 1 beneath the cross-saddle, the pump outlet 29 and exhaust return pipe 30 being connected by flexible pipes 31, 32 to input and exhaust passages 33, 34 in the saddle 5, and a valve block or casing VB which incorporates the valve means and is attached directly to the front of the saddle. The work table 3 moves in slide ways 11, 12, Fig. 2, in the saddle 5 which is formed with V-ribs 13 mounted in slide ways in the frame 1. The cylinder 14 is formed in three sections comprising two rectangular cylinder blocks 19, Fig. 1, and a central tube 20. The passage ways 33, 34 extend inwardly from the front of the saddle 5 and in addition passages 36, 37, Fig. 2, respectively constitute continuations of passages 17, 18 formed in the cylinder blocks 19. The valve block is formed with passage ways 38-41, Fig. 16, which register with the passages in the saddle 5 and comprises a main section 48, Fig. 1, a cross feed section 49 and an intermediate or transfer section 50. The main section 48 is bored at 55, Fig. 16, and accommodates a reverse piston valve 56 comprising three connected pistons 57, 58, 59 for opening and closing ports 61 - 64 and thus controlling the flow of oil into and from the two opposite end sections of the driving cylinder 14. The cross feed section 49 is bored at 65, Fig. 16, for a piston valve 66 comprising three connected pistons 67, 68, 69 controlling exhaust ports 70, 71 and ports 72, 73 regulating the flow to the upper and lower feed ram cylinders 76, 77, each containing a hydraulic ram 80 having a rack. 81 in mesh with a pinion 82 which operates the saddle 5. The inner and outer ends of the cylinders 55, 65 are connected respectively by passage ways 78, 79 and a pilot reverse valve 84 is provided in a vertically disposed cylinder in the part 48 to control the two reversing piston valves 56. 66. Two longitudinally adjustable dogs 91, 92, Fig. 16, are provided to operate the valve 84 through tappets 88 the valve 84 being prevented from turning too freely by a spring pressed ball. A manually operable valve 97 is provided in a vertical cylinder in section 48 to control the speed of traverse. A cross feed choke valve 104 is provided by which the cross feed may be cut out when required and a piston stop valve 109 to arrest the table at the end of a traverse to the right. The valve 109 is connected by a rod 112 with a guide piston 113 the outer end of which is connected by a short link 116 to a spring- controlled operating lever 117. The lever 117 is normally held inoperative by a detent 121 cooperating with adjustable trip dogs 124 to release the lever 117. The cross 'feed screw 9, Fig. 16, is engaged in a nut 131 fixed to the main bed 1, its rear end being mounted in the saddle 5 while the front end carries a hand-wheel 10, Fig. 1. Spring controlled pawls-co-operating selectively with an internally toothed ratchet wheel are oppositely arranged at the back of the hand wheel 10 the ratchet wheel being secured to a link mounted on a bush carried by a crank pin 148, Figs. 1 and 16, adjustable in a disc 149 keyed to the spindle which carries the pinion 82. Pressure in the ram cylinders 76, 77 causes the racks 81 to reciprocate and motion is transmitted therefrom to the crank disc 149 and thence to the pawl-carrying member to rotate the feed screw 9. In operation, oil from the tank 24 is delivered through the passages 31, 33, 38 to the ports 157, 158, 159 controlling the auxiliary circuit, the traversing of the work table and the cross feed mechanism respectively. With the speed control valve 97 as shown, the table 3 traverses from right to left until the dog 92 strikes the tappet 88 and rotates the valve 84 through a right angle to reverse pressure conditions in the valve cylinder 55 and the traverse cylinder 14. The table then traverses from left to right until the dog 91 restores the original setting. The table can also be stopped at the right hand end of its travel independently of the point of application of the stopping impulse by means of the valve 109 and the trip mechanism 117, 124. The cross saddle 5 is moved automatically at every reversal of the table by the feed screw 9 operated from the feed rams 80 and the rack and pinion gearing 81, 82.